Biomedical subjects

S S Yang

Publications and source records attributed to S S Yang.

At least 91 records · Page 5Linked to original sources

PubMed1995

Histopathology of fetal diastrophic dysplasia.

We report on three cases of diastrophic dysplasia in second trimester fetuses and discuss the differential diagnosis and clinical, radiologic, and histopathologic findings. Manifestations of typical diastrophic dysplasia in infants and older patients include abnormal pinnae, scoliosis, and joint contractures; these were absent in the fetuses, in keeping with the tendency for the clinical and radiologic aspects of this disease to become more severe with age. The histopathologic characteristics of the cartilage appear to be similar in the fetus and older patient, and therefore may be useful in differentiating diastrophic dysplasia from other osteochondrodysplasias in the second trimester.

Cartilage↗

PubMed1995

Rupture of the flexor pollicis longus tendon after 30 years due to migration of a retained foreign body.

Delayed rupture of a flexor tendon in the hand due to the presence of a retained foreign body is rare. We present the case of a late flexor pollicis longus rupture 30 years after traumatic implantation of a glass fragment. The foreign body had migrated distally a distance of 4.5 cm from the site of the original injury and eroded into the flexor tendon sheath. Thumb function was restored with a flexor digitorum superficialis tendon transfer from the ring finger with excellent results.

Adult↗

PubMed1995

Early interferon therapy and abortion of posttransfusion hepatitis C viral infection.

We studied the role of an "early" 4-month course of interferon therapy on posttransfusion viral hepatitis C (PTH-C). Paired serum samples of 51 consecutive recipients, taken before and 7-20 days after blood transfusion, were prospectively tested for hepatitis C virus ribonucleic acid (HCV RNA) using the polymerase chain reaction assay. Seven recipients experienced seroconversion of HCV RNA after transfusion. Two of the seven patients underwent an early 4-month course of interferon alpha therapy at a dose of 3 mU per day for 5 days during the first week, then three times a week for the subsequent 15 weeks. The first patient was treated at a very early stage of acute PTH-C and responded well to interferon therapy. Acute PTH-C in the second patient was prevented by interferon therapy. Both patients had normal serum alanine aminotransferase levels and tested negative for anti-HCV and HCV RNA 12 months after the end of treatment. Four of the five patients not on interferon therapy developed abnormal serum alanine aminotransferase activities more than five times the normal upper limit (383 +/- 143 IU/L) at 2-18 weeks after transfusion. All four patients experienced seroconversion of anti-HCV, and three patients developed chronic hepatitis. This study suggests that early long-term interferon therapy has the potential to prevent PTH-C.

Adult↗

PubMed1995

Characteristics of a group of nonnucleoside reverse transcriptase inhibitors with structural diversity and potent anti-human immunodeficiency virus activity.

Current thrust in controlling the Acquired Immune Deficiency Syndrome (AIDS) focuses on antiviral drug development targeting the infection and replication of the human immunodeficiency virus (HIV), the causative agent of AIDS. To date, treatment of AIDS has relied on nucleoside reverse transcriptase inhibitors such as AZT, ddI, and ddC, which eventually become ineffective upon the emergence of resistant mutants bearing specific nucleotide substitutions. The Anti-AIDS Drug Screening Program of the NCI conducts and coordinates a high-capacity semi-robotic in vitro screening of synthetic or natural compounds submitted by academic, research and pharmaceutical institutions world-wide. About 10,000 synthetic compounds are screened annually for anti-HIV activity. Confirmed active agents are subjected to in-depth studies on range and mechanism of action. Emerging from this intense screening activity were a number of potentially promising categories of nonnucleoside reverse transcriptase inhibitors (NNRTI) with structural diversity but strong and reproducible anti-HIV activity. Over 2500 active compounds were evaluated for their inhibitory activity against a panel of both laboratory and clinical virus isolates in the appropriate established cell line or fresh human peripheral blood leukocyte and macrophage preparations. Out of these, 40 agents could be placed structurally in nine categories with an additional 16 unique compounds that share the characteristics of NNRTI. These NNRTIs were shown to inhibit reverse transcriptase enzymatically using homopolymeric or ribosomal RNA as templates. NNRTIs demonstrated similarity in their inhibitory pattern against the HIV-1 laboratory strains IIIB and RF, and an AZT-resistant strain; all were inactive against HIV-2. These compounds were further tested against NNRTI-resistant HIV-1 isolates. NNRTI-resistant HIV-1 isolates were selected and characterized with respect to the change(s) in the viral reverse transcriptase nucleotide sequence. Also, differential cross-resistance or sensitivity patterns to NNRTIs were studied in detail among NNRTI-resistant mutants. When tested in combination with AZT, all of the NNRTI's uniformly exhibited synergistic inhibition of HIV-1, suggesting that combination antiviral therapy of NNRTIs with AZT may be therapeutically promising for AIDS treatment.

Acquired Immunodeficiency Syndrome↗

PubMed1995

The NCI's AIDS antiviral drug screening program.

The Developmental Therapeutics Program (DTP) in the National Cancer Institute has an unique mission by serving as a resource for all academic and private research institutions, the National Institutes of Health in the USA, and the global scientific community in the quest for effective therapeutic agents for treating patients with Acquired Immune Deficiency Syndrome (AIDS) as well as for cancer patients. This communication will concentrate on the developmental therapeutic program on anti-AIDS drug discovery.

Acquired Immunodeficiency Syndrome↗

PubMed1995

Arthroscopic surgery of the knee in the geriatric patient.

There remains some controversy and confusion regarding arthroscopic surgery of the knee in the elderly population, particularly for patients with osteoarthritis. A retrospective review was undertaken of 105 knees in patients 60 years or older who had arthroscopy during a 4-year period. The surgical outcomes were evaluated using a postoperative knee scoring system at a mean followup period of 11.7 months. Good and excellent results were obtained in 65% of knees. The most significant predictors of good outcome were preoperative mechanical symptoms, such as those resulting from loose bodies or flap tears of the meniscus, and only mild articular degeneration seen at arthroscopy. A review of the literature reflects similar success rates. Although the results are equivocal by orthopaedic standards, in selected patients arthroscopic surgery can offer significant relief of acute symptoms and defer more extensive surgical procedures with minimal risk.

Aged↗

PubMed1995

Morphogenesis, biomass and oxytetracycline production of Streptomyces rimosus in submerged cultivation.

The minimal concentration of adenosine triphosphate (ATP) which could be detected with spectrophotometry, HPLC and luciferin-luciferase methods was 1.0 microM, 3.3 microM and 100 nM, respectively. In submerged cultivation, most Streptomyces rimosus TM-55 was in hyphae fragment form at 65 h, became short-rod mycelia at 166 h, and lysed at 504 h incubation. The ATP content had maximal value at 24 h, then gradually decreased during cultivation. The oxytetracycline potency increased as incubation occurred, had maximal potency 178.9 micrograms/ml at 166 h, and then gradually decreased. Morphogenesis was very important in oxytetracycline production in submerged cultivation of Streptomyces; short-rod mycelia had high oxytetracycline production.

Adenine Nucleotides↗

PubMed1995

[Amylase production of Streptomyces rimosus TM-55 and their 2-deoxyglucose resistant mutants].

Streptomyces rimosus TM-55 was treated with 3% ethyl melthylsulfonate for 60 minutes to generate mutants producing high amount of amylase, and 1,283 mutants were isolated from yeast extract starch (YS) medium containing 0.1% 2-deoxyglucose. Amylase activity was primarily screened by clear zone formation on YS medium after spraying with iodine solution. Two mutants designed as D-35 and D-62 had higher amylase activity than that of the parent strain. Amylase activity of the mutants in the YS broth was 2.97- and 3.45-fold of the parent strain, respectively. With the addition of 0.1% lactose, and 2-deoxyglucose, amylase activity of the mutants D-35 and D-62 was 27-73% and 4-7% higher than that of the parent strain. With the addition of 0.1% sucrose, amylase activity of the mutant D-35 was 18.37% lower than that of the parent strain. Moreover, with the supplement of 0.1% glucose, amylase activity of both the mutants D-35 and D-62 was 3.67 and 3.40 fold of the parent strain.

Amylases↗

PubMed1994

Determination of aldicarb, aldicarb sulfoxide and aldicarb sulfone in tobacco using high-performance liquid chromatography with dual post-column reaction and fluorescence detection.

A screening method for the determination of aldicarb (AS) and its sulfoxide (ASX) and sulfone (ASN) metabolites in tobacco at low ppm levels is described. Tobacco samples are extracted using methanol with the aid of sonication at ambient conditions. The extract is filtered and then injected into a high-performance liquid chromatograph equipped with a dual post-column reaction system and a fluorescence detector. Chromatographic separation is performed on a C18 column with a mixture of methanol-acetonitrile-water containing 0.1% of triethanolamine as the mobile phase. Triethanolamine is added to improve peak shape of AS residues and to reduce the undesired interaction between residual silanols and interferences, mainly amino acids and other amines. The average recoveries for AS residues spiked in tobacco are higher than 95% for AS, 91% for ASN and 85% for ASX at levels of 0.5-10 ppm (w/w). The detection limit is 0.5 ppm for each of the target compounds.

Aldicarb↗

PubMed1994

Impact of screening blood donors for hepatitis C antibody on posttransfusion hepatitis: a prospective study with a second-generation anti-hepatitis C virus assay.

BACKGROUND: Hepatitis C is the major cause of posttransfusion hepatitis. Blood components that are positive for antibody to hepatitis C virus (anti-HCV) can transmit posttransfusion hepatitis. STUDY DESIGN AND METHODS: To investigate the effect on posttransfusion hepatitis of screening blood donors with a second-generation test for anti-HCV, 249 transfusion recipients who underwent cardiovascular surgery were prospectively followed. Six recipients who were positive for anti-HCV before transfusion and 51 subjects with incomplete follow-up were excluded from this study. RESULTS: Eleven (13.8%) of 80 subjects who received unscreened blood had two successive serum alanine aminotransferase levels > 90 U per L. Seven (8.8% of total) developed anti-HCV and HCV RNA and two (2.5% of total) developed IgM antibody to cytomegalovirus (IgM anti-CMV). By contrast, 3 (2.7%) of the 112 subjects who received anti-HCV-screened blood had two successive serum alanine aminotransferase levels > 90 U per L. None of these three developed anti-HCV and HCV RNA, but two (1.8% of total) showed the development of IgM anti-CMV. The study shows that screening for anti-HCV in blood donors with a second-generation test almost abrogated posttransfusion viral hepatitis C. CONCLUSION: After anti-HCV screening, other body fluid-transmitted viruses such as CMV may become important in posttransfusion hepatitis.

Adolescent↗

PubMed1994

Chronic elemental mercury intoxication: clinical and field studies in lampsocket manufacturers.

Four workers chronically exposed to elemental mental mercury in a lampsocket manufacturing factory were studied. The clinical manifestations were severe in one, mild in another, and suspicious in the remaining two. Correlation between severity of clinical features and increased urinary mercury concentrations was found. The time weighted average mercury concentrations were 0.945 mg/m3 and 0.709 mg/m3 for two workers in one room and 0.225 mg/m3 in the other. After stopping exposure, the workers recovered spontaneously or with D-penicillamine treatment within six months. It is concluded that recovery from chronic elemental mercury intoxication may be complete when patients are removed early from the exposure environment. The hazard of mercury intoxication in recycling of waste substances is emphasised.

Adult↗

PubMed1994

Doppler echocardiography in normal functioning valve prostheses.

Even though there has been some criticism regarding the Doppler evaluation in prosthetic valves because of inter-observer and intra-observer variability, among other factors, and Doppler study has a tendency to have falsely high gradients compared to invasive studies, especially mechanical aortic prostheses, Doppler evaluation can provide reliable hemodynamic information about valve function. This test may be particularly useful if used serially, when baseline values are known. Doppler measurement of gradient and valve area has an expected normal range that is specific for the prosthetic type, size, anatomical position, and chronological age. Clearly, a database involving these aspects is needed to provide a more accurate normal range. This study is intended to provide guidance for echocardiographers.

Adult↗

PubMed1994

Prenatal screening for cardiac anomalies: the value of routine addition of the aortic root to the four-chamber view.

OBJECTIVE: To determine whether the addition of the aortic-root view would detect more congenital cardiac anomalies than a standard four-chamber view alone. METHODS: The study included fetuses of 14 weeks' gestation or more who were scanned in our unit during a 28-month period. Outcome information was obtained from postnatal echocardiograms and autopsies. Abnormal hearts were classified as to whether the four-chamber or aortic-root view was abnormal. RESULTS: There were 5967 fetuses in whom a four-chamber view could be obtained. In 5111 of these, an aortic-root view could also be obtained. The four-chamber view detected 24 (47%) of the 51 fetuses with abnormal hearts. Adding the aortic-root view increased the sensitivity to 78%. CONCLUSIONS: Visualization of the aortic root is a quick and easy means of evaluating the aortic outflow tract during routine scanning. Adding the aortic-root view to the standard four-chamber view will result in the detection of most cardiac anomalies prenatally.

Echocardiography↗

PubMed1993

Skeletal histopathology in fetuses with chondroectodermal dysplasia (Ellis-van Creveld syndrome).

Chondroectodermal dysplasia (CED) is an uncommon autosomal recessive disorder and one of the short rib polydactyly syndromes (SRPS). It is characterized by acromelic and mesomelic shortness of limbs, postaxial polydactyly, small chest, ectodermal dysplasia, and in many cases, congenital heart defects. Controversy exists over possible changes in the growth plate. With the advent of ultrasonographic examination, increasing numbers of fetuses with osteochondrodysplasias are examined by pathologists. Since histopathologic examination of the skeletal system is useful in defining various osteochondrodysplasias and it has not been described in the fetus with CED, we herein describe 3 cases of fetal CED with emphasis on skeletal histopathology. All 3 pregnancies were terminated at 22-23 weeks because of ultrasonographic demonstration of short limbs and growth retardation. Radiologically, each fetus had acromelic and mesomelic shortness of long bones with smooth round metaphyses, vertically short iliac bones, short ribs and normal vertebrae. These findings are similar to those described in the larger newborn infant with CED. Histopathologically, the cartilage of the long bones showed chondrocytic disorganization in the physeal growth zone. The findings are dissimilar to those of larger infants and older children in whom chondrocytic columnization has been seen in the central physis and disorganization in peripheral physis. Furthermore, a variable degree of chondrocytic disorganization was also seen in the central physeal growth zone of vertebrae in these fetuses. Other findings noted at fetopsy were: polydactyly in all 3 cases, congenital heart defect in 2 and an abnormal frenulum in one case. The foregoing phenotypic and radiographic manifestations and skeletal histopathology help separate CED from other SRPS.

Bone and Bones↗

PubMed1993

Listeriosis of the placenta: clinicopathologic study of seven cases.

OBJECTIVE: The purpose of our study was to evaluate the usefulness of placental examination in the diagnosis of prenatal listeriosis. STUDY DESIGN: Over a 7-year period, 4597 placentas with clinical indications for examination were retrospectively studied for morphologic evidence of listeriosis. The microbiology laboratory file records of positive Listeria monocytogenes cultures were used to confirm the diagnosis. The clinical records were studied for manifestations of the infection both in the neonates and in the mothers. RESULTS: Seven placentas were identified as having listeriosis. The presence of macroabscesses, as opposed to microabscesses, was the most characteristic finding in this study, and the silver impregnation method was more reliable in identification of the bacilli in the tissue sections than the tissue Gram stains. CONCLUSIONS: Listeriosis could be diagnosed by placental examination alone, and this examination frequently strengthened the clinical diagnosis. When the infection was not suspected clinically, the examination helped us reach the correct diagnosis.

Adolescent↗

PubMed1993

Strategy and implementation of a system for protein engineering.

This paper describes an overall view of an industrial protein engineering project from conception to successful completion. The choice of rational design was determined by the availability of an excellent three-dimensional crystal structure and the availability of information in the literature to define a strategy. The design strategy was refined extensively during the course of the project. The development of methods for mutagenesis, expression, verification, purification, and characterization of mutant enzymes is dictated in part by the enzyme property one chooses to modify and must be rapid yet accurate. Such an approach would be applicable to improve the stability of any other protein or enzyme. Using this approach, we successfully increased the stability of subtilisin BL over 10-fold at 50 degrees C with an overall success rate greater than 60%.

Bacillus↗

PubMed1993

Protein enrichment of sweet potato residue with co-culture of amylolytic fungi by solid-state fermentation.

Protein enrichment of sweet potato residue with amylolytic moulds by solid-state fermentation was higher than that obtained with amylolytic yeasts. The optimum initial moisture content for protein enrichment was 66% to 75%. Incrementally added nitrogen sources to the culture at zero time and at 24 h considerably improved the final protein content. During the cultivation, the moisture, ash and ATP contents increased, while the pH value decreased. A 1:1 co-culture of amylolytic mycelial fungi yielded a product with 32.4% crude protein after 4 days incubation at 30 degrees C.

Journal Article↗

PubMed1993

Cystic enlargement of the iliopsoas bursa causing venous obstruction as a complication of total hip arthroplasty. A case report.

The authors report an unusual complication of total hip arthroplasty. A patient developed significant swelling and discomfort in the left lower extremity 4 1/2 years following a left total hip arthroplasty. Magnetic resonance imaging and venography demonstrated a large intrapelvic mass compressing the external iliac vein. An arthrogram revealed a cystic cavity consistent with an iliopsoas bursa in communication with the hip pseudocapsule. Two aspirations of the bursa led to resolution of the cystic enlargement and symptoms. An enlarged iliopsoas bursa should be considered in the differential diagnosis of hip pain or extremity swelling after total hip arthroplasty.

Adult↗